1. Field of the Invention
The present invention relates to a charge removal brush for removing charges from the transfer drums and papers in a Xerography image forming apparatus, such as a copying machine and a printer, and from residual toner from the photoreceptor in the cleaning unit in the same apparatus.
2. Discussion of the Prior Art
In Xerographic copying machines, for example, a charge removal roll or a charge removal brush is used for removing charges from residual toner in the stage of cleaning the photoreceptor, which follows the image transfer stage where a toner image is transferred to a paper. The same is used for removing charges from the transfer drums and from a paper in a paper transfer path.
In one of the known fur brushes for charge removal, conductive fibers are used for the brush fur, and the conductive fibers are earthed through a metal shaft.
Published Unexamined Japanese Patent Application No. Hei. 1-217387 discloses a cleaning brush for charge removal in which a band-like woven cloth with conductive fibers planted therein is used for the fur brush, and it is wound on a metal shaft.
The cleaning brush not only removes charges of the residual toner from the photoreceptor but also agitates the residual toner. For the brush fur or the long filamentous elements for the brush, the fibers are entirely planted around of the metal shaft. The metal shaft is driven to rotate in a state the tips of the fibers are in contact with the photoreceptor.
Also in the charge removal brushes used for other components and the like, to secure good charge removal capability, it is desirable that the fibers are uniformly planted around the metal shaft, and the metal shaft is driven to rotate.
The known charge removal brush in which the long filamentous elements of the brush fur are planted around the metal shaft suffers from the following problems.
It is difficult to plant the long filamentous elements uniformly around the metal shaft. Further, it is difficult to bring the brush fur or long filamentous elements into contact with the photo receptor in a state that electric resistance between the brush fur and the shaft is small. If the fur brush satisfying those conditions is manufactured with taking the difficulty, the result is to increase cost to manufacture.
In the case of the cleaning brush disclosed in Published Unexamined Japanese Patent Application No. Hei. 1-217387 in which the band-like woven cloth is wound around the metal shaft, the manufacturing of the cleaning brush is easy, but it is difficult to reduce the electrical resistance between the brush fur and the metal shaft and hence to secure a good electrical conduction therebetween. In one of the possible approaches, the base cloth are entirely made of conductive fibers. Coating of the conductive resin is used for bonding them. The approach succeeds in reducing electrical resistance, but fails in reducing the cost to manufacture since the conductive fibers are expensive. To solve this problem, the conductive fibers are used mingled with the lengthwise threads of the base cloth. However, the electric resistance between the brush fur and the metal shaft is large at locations where the lengthwise threads of the woven cloth are not conductive. Further, in this charge removal brush, metal fibers are used for the conductive fibers. The metal fibers are not adapted to the widthwise threads when woven. The long filamentous elements of the brush fur, when woven, are erected in a bifurcated or divided fashion. The result is a nonuniform distribution of the planted long filamentous elements of the fur brush.